Immigration Site

Hello,

Can any one please help me understand "Processing Date" from UCIS website for 140.
Is it Receipt Date and Notice date?

My 140 was filed in TX and the prcocessing date shows as July 23,2007. My Receipt date is Aug 7th 2007 and Notice date is Sep 27th 2007.

Please help me understand these dates.

Thanks in advance.
Venky